This invention relates to heat exchanger fins coupled to a thermoelectric module.
A thermoelectric module is a device which converts a heat differential directly into electrical energy through the Seebeck effect, or when operated in reverse, converts electrical energy into a heat differential through the Peltier effect. A thermoelectric module generally uses semiconductor p-n junctions sandwiched between a pair of flat parallel substrates, constructed of a material having relatively low electrical conductivity and high thermal conductivity, such as aluminum oxide. Each thermoelectric module includes a hot side, the side that absorbs heat, and a cold side, the side that expels heat. The thermoelectric module is typically mounted between two parallel plates, one plate on the hot side of the thermoelectric module and one plate on the cold side of the thermal electric module. The cold-side plate generally includes cooling fins and the hot-side generally includes heating fins. The heating fins transfer heat from a heat source toward the thermoelectric module and the cooling fins transfer the heat away from the thermoelectric module after the heat has crossed the thermoelectric module. As the cooling fins on the cold-side plate and the heating fins on the hot-side plate transfer heat across the thermoelectric module, the thermoelectric module generates an electric voltage. It is important that the cold-side plate and the hot-side plate maintain a close thermal contact with the thermal electric module to maximize the heat transfer rate across the thermoelectric module. Maximizing the heat transfer rate across the thermoelectric module maximizes the efficiency and electric output of the thermoelectric module.
A common prior art method for mounting the thermoelectric module between the cold-side plate and the hot-side plate is to use bolts to connect the plates together with the thermoelectric module compressed in between. Mounting the thermoelectric module between the plates with bolts in this manner results in bending moments on the plates, causing the plates to bow apart at the center. The bowing of the plates reduces the thermal contact area between the plates and the thermal electric module, thereby decreasing its efficiency. The thickness of the plates could be increased to stiffen the plates against bowing. However, increasing the thickness of the plates would increase the thermal resistance of the plates, thereby decreasing the heat transfer rate across the thermoelectric module.
In addition to decreasing the efficiency of the thermoelectric module, simply compressing the thermoelectric module between the plates with bolts applies non-uniform compressional forces to the thermoelectric module. These non-uniform compressional forces may cause high pressure regions to develop on the thermoelectric module, causing the thermoelectric module to fracture during the assembly process or during operation.